Thickening skin falling off lethargic frogs and toads in flecks. Struggles with breathing and eating. An immune system under attack shutting the body down.
Those are telltale signs of chytridiomycosis, a lethal fungal disease that’s been called an “epidermal epidemic” leading to the extinction of dozens of amphibian species worldwide.
It hasn’t been detected yet in Canada’s middle province — but that isn’t necessarily because it isn’t in Manitoba.
“It is quite literally everywhere on our continent …. There’s no way we don’t have this pathogen here,” said Jackie Tran, a graduate student sampling frogs and salamanders across southern Manitoba.
“There’s reported presence everywhere around our province. Now, that doesn’t mean we don’t have the pathogens here, it just means we haven’t been on top of surveillance up until now.”
Chytrid in frogs is caused by the fungal pathogen Batrachochytrium dendrobatidis; in salamanders, by Batrachochytrium salamandrivorans.
The latter, believed to have originated in East Asia, surfaced in the past couple decades and has decimated local populations of salamanders in parts of Europe.
It hasn’t made the leap to North America yet, that scientists know of.
Where the variety that infects frogs and toads first emerged remains unclear, though there are signs it was present in Brazil and Asia for more than a century before popping up around the world, in large part because of the trade in exotic pets.
Chytrid is directly responsible for the extinction of at least 90 species, and tanking numbers in more than 500 others.
That’s one of the reasons it’s been described as “the worst infectious disease ever recorded among vertebrates” (any creature with a spine). It’s become more established in the U.S. and Canada in recent years.
A blue-spotted salamander emerges from beneath a woodpile in northwestern Ontario last summer. The fungal infection hasn’t been confirmed in salamanders in North America yet. (Colby McGilvray/CBC)
Nearly half of Alberta frog populations sampled between 2006-10 came back positive for chytrid. Studies from around the same time in British Columbia found it present in one of 10 amphibians sampled, with northern leopard frogs among those worst hit.
That species is federally listed as endangered in parts of Western Canada. In Manitoba, it’s listed as a species of special concern.
The leopard frog — one of 16 amphibian species in Manitoba historically — has seen population declines across Canada in recent decades. And there’s suspicion that chytrid might have been the culprit behind a marked drop in Manitoba numbers five decades ago.
The leopard frog range in Manitoba contracted after “heaps of dead and dying frogs” up to a metre high were observed along shores of some wetlands in Manitoba.
A northern leopard frog lurks along the edges of a lake near the border of Manitoba and Ontario in September 2026. (Bryce Hoye/CBC)
No one sampled or scooped up any of those frog corpses for posterity, so while chytrid is considered a plausible explanation, it remains speculation.
Tran suggests the thus-far chytrid-free designation for Manitoba might be more of a mirage than a mirror of any special conservation action going on in the province keeping the disease at bay.
Jackie Tran, a master’s student at Brandon University, stands next to a wetland in Sandilands Provincial Forest in south eastern Manitoba on Oct. 1. His research is focused on determining for the first time whether a deadly fungal pathogen has infected populations of amphibians in Manitoba, such as northern leopard frogs and tiger salamanders. (Bryce Hoye/CBC)
“That’s kind of been taken as a sign to not prioritize this research,” he said.
It’s been confirmed in frogs in Ontario, including in the northwest, not far from the Manitoba border, as well as in the Northwest Territories, North Dakota and Minnesota. Saskatchewan had one confirmed case in 2007, Tran says.
Tran swabs a gray treefrog as part of his research focused on confirming whether Batrachochytrium dendrobatidis has made it into Manitoba amphibian populations. (Submitted by Jackie Tran)
There’s reason to believe the risk to amphibians on the Prairies could be increasing.
“With a changing environment, a changing climate, things could get a lot worse,” Tran said.
He used geographic modelling data to identify a range of wetland amphibian habitats where the pathogens could thrive.
Tran’s work marks the beginning of a proactive monitoring program at Brandon University that his supervisor plans to carry on.
“If we can get out front of this, this can help sort of limit some of these declines,” said Pamela Rutherford, associate professor in the department of biology at BU.
Tran is her first graduate student doing this kind of work, which is part of a broader pathogen monitoring program that started in the U.S., Rutherford says.
Tran sampled a variety of the 16 amphibian species that call Manitoba home, including wood frogs, such as those shown here in a southern Manitoba wetland. (Submitted by Jackie Tran)
Pathogens spread well in wetlands degraded by human activity, Rutherford says, which is why the component of Tran’s work identifying those kinds of habitats could have value beyond his project.
“This also gives us a more general sense of what the health of wetlands are now for the systems that he [Tran] looks at, but that has much broader implications for the health of everything,” Rutherford said.
“The health of the wetland tells you about not just how the frogs are doing, but it tells you how the fish … how the insects are doing, how the plants are doing, and so it’s all interrelated,” she said.
“The health of wetlands is also directly connected with human health as well: healthy wetlands, healthy environments.”
Rutherford says if Brandon researchers confirm the pathogen in amphibians in Manitoba, there’s a glimmer of hope that those amphibians might not be consigned to oblivion after all.
A baby American toad crawls across moss in northwestern Ontario in August 2017. (Bryce Hoye/CBC)
Results emerging from field experiments run by the Wilder Institute and the Calgary Zoo suggest young leopard frogs can be inoculated against the worst effects of chytrid.
They gave a few dozen young frogs, from a B.C. population overrun with chytrid, baths in a diluted itraconazole solution.
More than a quarter of the frogs they treated survived winter, says Lea Randall, senior manager conservation programs at the Wilder Institute, compared with an estimated half a per cent of untreated frogs.
“We had about 60 times the overwinter survival for treated frogs, which confirms that chytrid fungus is what has hampered our reintroduction efforts until now,” Randall told CBC News via email.
“We are scaling up this treatment in 2026 and are optimistic that this will lead to improved success in our reintroduction efforts.”
An American bittern eats a barred tiger salamander. (Bryce Hoye/CBC)
Tran hopes Manitoba is in a position to leverage that success, should its cold-blooded critters need help.
“We tend to mourn things when we’ve already lost it, and this disease research is just one component of trying to protect that and prevent that from happening,” he said.
